Author Jeff Speck's new book "Walkable City: How Downtown Can Save America, One Step at a Time" has some eye-opening information that could have you revising your New Year's resolutions.

Forget about your long list of vows to get in better shape, be more ecoconscious, do more to support the local economy, improve your social life and save money.

According to Speck, you can accomplish all those goals — and many more — just by making an effort to drive less.

Many Americans spend a shocking proportion of their household income on getting around by car. The average American family spends $14,000 a year to drive multiple cars, with the typical family paying more for transportation than housing.

That seemed unbelievable to me until I did some quick calculations.

My family recently finished making the last payments on our car and small truck, but if we still had those payments, the cost of our vehicles, insurance, maintenance and gas would be almost exactly equal to our mortgage.

With two working parents in our household, we're not about to jettison one of our vehicles, but at least it's made me lose my desire to buy a new car.

Speck notes that 85 percent of spending on cars and gas leaves the local economy. In cities like bike- and pedestrian-friendly Portland, residents have more money to spend going out to restaurants, drinking craft beer and socializing.

Walking or biking also provides great benefits when it comes to getting in better shape. One study found that 35 percent of San Diego residents in highly walkable neighborhoods were overweight, compared to 60 percent in not-so-walkable parts of the city, Speck said.

Even if you just walk to and from the bus stop, you'll be doing yourself a world of good. The U.S. Centers for Disease Control and Prevention estimates that transit users are three times as likely to get a total of 30 minutes of daily physical activity, Speck said.

One study showed that drivers who switched to public transportation lost an average of five pounds, he said.

While highlighting the benefits of walking, biking and riding the bus, "Walkable City" contains enlightening information about what pushes many people to drive.

Speck discusses the key concept of the "useful walk" (or bike or bus ride). The key to getting people to walk regularly is to make the walk serve a purpose.

People need to be within walking distance of work, shopping and home.

Zoning has done much to destroy the useful walk by separating housing from other uses, Speck says.

Luckily, planners and developers are recognizing the importance and value of mixed-use development. Downtown buildings, for example, can have shopping on the first floor with apartments or condominiums above.

Speck said many cities are reinstating the useful walk and revitalizing their downtowns by creating housing there.

Some cities have experimented with creating pedestrian-friendly downtowns by banning automobile traffic. Speck said these experiments have been almost universal failures and have devastated downtown economies.

The key is to give drivers appropriate space, while also respecting the needs of pedestrians, cyclists and bus riders, he said.

Right after finishing "Walkable City," I decided to ride my bike to the post office instead of driving, as I had planned.

On my "useful bike ride," I waved at my neighbor, mailed a package, saved on gas, didn't pollute the environment, supported a local coffee shop by buying hot chocolate, got some exercise and fresh air — and enjoyed the satisfying feeling of keeping all my New Year's resolutions.